"Oh, there was talk of the blood ties between Baratheon and Targaryen, of weddings a hundred years past, of second sons and elder daughters. No one but the maesters care about any of it. Robert won the throne with his warhammer."
This is in the year AL 299. We know that the daughter of Aegon V married an unnamed Baratheon. The only known child of that union was Steffon Baratheon, father to Robert, Stannis and Renly. Like many, I have assumed that the Baratheon claim to Targaryen blood was based on the marriage of Egg's daughter to some Baratheon. But that is NOT the claim that Renly cites.
He talks of "weddings a hundred years past, of second sons and elder daughters" as the root of the Baratheon/Targaryen blood link. Ageon V was born in AL 199, so he had no kids to get married a hundred years past--and the phrase "elder Daughter" suggests more than one, but Aegon V only had one daughter and Jaehaerys II was his second son.
Renly's time-frame also rules out Orys Baratheon as the source of the link his House and House Targaryen.
So what is the source of Baratheon legitimacy to the IT that Renly cites?
The timing seems to suggest the children of Aegon IV (Aegon the Unworthy) or his granchildern. Of them, the only one to have a second son and more than one daughter was Maekar I, Egg's dad. Aerion (Brightflame) was the second son and Rhae was the eldest daughter. Their mates and fates of their children is unknown. Did they marry Baratheons? Or was it another Baratheon/Targaryen paring that Renly cites? Or did Renly lack a sense of his own history and anything in the past seemed like a hundred years ago to him?
Of course in AFFC, Measter Aemon tells Sam that it was through Egg's daughter that the Baratheon's had some Targ blood, so it is possible that Renly just had no idea what he was talking about, but the line "weddings a hundred years past, of second sons and elder daughters" seems pretty specific and none of the details fit the marriage of Aegon V's daughter to some unnamed Baratheon.
It is an odd little mystery. Any ideas?